/*
 * Copyright (C) 2012 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import java.util.ListIterator;

/**
 * An iterator that transforms a backing list iterator; for internal use. This avoids the object
 * overhead of constructing a {@link Function} for internal methods.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class TransformedListIterator<F, T> extends TransformedIterator<F, T> implements ListIterator<T> {
    TransformedListIterator(ListIterator<? extends F> backingIterator) {
        super(backingIterator);
    }

    private ListIterator<? extends F> backingIterator() {
        return Iterators.cast(backingIterator);
    }

    @Override
    public final boolean hasPrevious() {
        return backingIterator().hasPrevious();
    }

    @Override
    public final T previous() {
        return transform(backingIterator().previous());
    }

    @Override
    public final int nextIndex() {
        return backingIterator().nextIndex();
    }

    @Override
    public final int previousIndex() {
        return backingIterator().previousIndex();
    }

    @Override
    public void set(T element) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void add(T element) {
        throw new UnsupportedOperationException();
    }
}
